@mixin absCenter {
      position: absolute;
      left: 0;
      top: 0;
      right: 0;
      bottom: 0;
      margin: auto;
}

@mixin clearBoth {
      content: "";
      display: block;
      overflow: hidden;
      clear:both;
}

@mixin jianrong( $arg : all 0s ){
      -webkit-transition: $arg;
      -moz-transition: $arg;
      -ms-transition: $arg;
      -o-transition: $arg;
      transition: $arg;
}